Condensation Reaction Of Formaldehyde Research Articles

Solvatochromism mechanism of perylene diimide radicals stabilized by low barrier hydrogen bond and detection of formaldehyde in real food samples

Formaldehyde (FA) is widely used for food preservation and whitening because of its preservative and bleaching effects. Excessive FA seriously endangers human health, so monitoring FA-treated food is of great significance for food safety. In this paper, perylene diimide radicals with the chirality (BTFPDI) and water-solubility (TFPDI-bPEI) were designed respectively based on our previous studies. Property of solvatochromism induced by these perylene diimide radicals aggregation was demonstrated by the concentration and temperature dependent absorption spectrum and the circular dichroism spectrum. Further the colorimetric monitoring of trace FA in gaseous and liquid was realized by the condensation reaction of FA with amine to induce TFPDI-bPEI aggregation. After the addition of FA, TFPDI-bPEI molecule aggregated in aqueous solution due to the specific reaction of a large number of –NH2 groups with FA, resulting in a blue-shift of the maximum absorption peak from 780 nm to 561 nm, and the detection limit as low as 0.86 μM to FA and the response time of only 20 s. This method could further detect FA in food with good recoveries and detect FA in contaminated food samples.

Synthesis, characterization and anticancer activity of Ni(II), Cu(II), Pd(II) and Au(III) complexes derived from novel Mannich base

AbstractNew four complexes of Ni(II), Cu(II), Pd(II), and Au(III) were derived from the tridentate ligand 3‐((3‐(4‐hydroxyphenyl)‐5‐mercapto‐4H‐1,2,4‐triazol‐4‐yl)(3‐oxobutyl)amino)naphtho[2,3‐b]furan‐2(3H)‐one (L), which synthesized using condensation reaction of formaldehyde, acetone, and secondary amine (Mannich reaction). The secondary amine is a heterocyclic compound possesses two rings, naphthafuran and triazole, both rings prepared through intermolecular cyclization reactions. Considering that naphthafuran‐2‐one derived from α‐amino nitrile. The α‐amino nitrile compound contains the other triazole ring which illustrated to the structure through successive steps. The compounds were characterized using elemental analysis (C.H.N.S), FT‐IR, ultraviolet–visble spectroscopy, thermal gravimetric analysis (TGA), flame atomic absorption, molar conductivity, and magnetic susceptibility measurements. Accordingly, the probable geometries of the complexes were suggested as square planner, and they have electrolytic nature. Thus, chemical formula; [NiLCl]Cl·6H2O, [CuLCl]Cl·2H2O, [PdLCl]Cl·2H2O, and [AuLCl]Cl2·3H2O. Cytotoxic effect was studied on brain cancer cell line (AMJM cell line) at different concentrations for L and complexes. The results showed that gold(III) complex has the highest cytotoxicity among all compounds.

Metal-doped M-NH4-PW catalyst with enhanced electron transfer for formaldehyde-propylene condensation to 4-methyl-1,3-dioxane

Recognizing and modifying the acid property-dependent catalytic characteristics of catalysts are of great importance for Prins condensation reaction. Herein, a series of metal-doped M-NH4-PW catalysts (M=Pt, Fe, Ir, Ru) are successfully synthesized for Prins condensation reaction of formaldehyde and propylene to produce 4-methyl-1,3-dioxane. Our findings demonstrate that the catalytic performance of M-NH4-PW catalysts is influenced by the chemical nature of metal site properties with different electron transfer abilities. Specifically, the new Lewis acid decorated by Pt metal on 4-H site is more favorable for the selective adsorption of formaldehyde and activation of its CO bond. Additionally, the synergistic effect between Pt metal sites and nearby O in [PW12O40]3− promotes the formation of CC bonds between protonated formaldehyde and propylene. Consequently, the Pt-NH4-PW catalyst exhibits high conversion (> 80 %) and simultaneous selectivity towards 4-methyl-1,3-dioxane selectivity (65 %). This strategy may provide valuable insights for developing efficient multifunctional catalysts for Prins condensation reactions.

Tailored extraction and ion mobility-mass spectrometry enables isotopologue analysis of tetrahydrofolate vitamers

Climate change directs the focus in biotechnology increasingly on one-carbon metabolism for fixation of CO2 and CO2-derived chemicals (e.g. methanol, formate) to reduce our reliance on both fossil and food-competing carbon sources. The tetrahydrofolate pathway is involved in several one-carbon fixation pathways. To study such pathways, stable isotope-labelled tracer analysis performed with mass spectrometry is state of the art. However, no such method is currently available for tetrahydrofolate vitamers. In the present work, we established a fit-for-purpose extraction method for the methylotrophic yeast Komagataella phaffii that allows access to intracellular methyl- and methenyl-tetrahydrofolate (THF) with demonstrated stability over several hours. To determine isotopologue distributions of methyl-THF, LC-QTOFMS provides a selective fragment ion with suitable intensity of at least two isotopologues in all samples, but not for methenyl-THF. However, the addition of ion mobility separation provided a critical selectivity improvement allowing accurate isotopologue distribution analysis of methenyl-THF with LC-IM-TOFMS. Application of these new methods for 13C-tracer experiments revealed a decrease from 83 ± 4 to 64 ± 5% in the M + 0 carbon isotopologue fraction in methyl-THF after 1 h of labelling with formate, and to 54 ± 5% with methanol. The M + 0 carbon isotopologue fraction of methenyl-THF was reduced from 83 ± 2 to 78 ± 1% over the same time when using 13C-methanol labelling. The labelling results of multiple strains evidenced the involvement of the THF pathway in the oxygen-tolerant reductive glycine pathway, the presence of the in vivo reduction of formate to formaldehyde, and the activity of the spontaneous condensation reaction of formaldehyde with THF in K. phaffii.

Kinetics and optimization studies of modified VPO/γ-Al2O3 catalyst prepared in situ for cross-aldol condensation

Modified VPO/γ-Al2O3 catalysts were prepared in situ for the first time and applied to the aldol condensation reaction of acetic acid and formaldehyde. VPO/γ-Al2O3 exhibited excellent catalytic performance at a calcination temperature of 350 °C.

Gradient Concentration Control of Active Components on the Industrial Cs-P/γ-Al2O3 Catalyst

For supported catalysts, it is particularly important to ensure the effective loading of the active component on the support. A new industrial Cs-P/γ-Al2O3 catalyst with controllable distribution of active components was developed and applied to the aldol condensation reaction of methyl propionate and formaldehyde. The distribution of active components was controlled by adjusting the preparation conditions, especially the adsorption time, to form the catalyst with a gradient concentration of active components, which had been confirmed by the EMPA and SEM-EDS characterization. In addition, the kinetic equations including pseudo-first- and pseudo-second-order kinetic models as well as isotherm equations based on Freundlich and Langmuir models were used to describe the adsorption process to provide valuable process parameters for industrial production of catalysts.

A novel and environmentally friendly NASICON-type material: Efficient catalyst for condensation of formaldehyde and acetic acid to acrylic acid and methyl acrylate

The development of environmentally friendly and efficient catalysts for the production of essential chemicals has always been a desirable goal for technology in the chemical industry. In this paper, we fabricated a kind of sodium (Na) super ionic conductor (NASICON)-type materials (H1-xTi2(PO4)3-x(SO4)x) with different Ti/P ratios through tuning titanium content in synthetic mother liquor, and applied them to the aldol condensation reaction of acetic acid (HAc) and formaldehyde (FA) to acrylic acid (AA) and methyl acrylate (MA), which has never been not reported in previous researches. More importantly, these novel catalysts have showed their tremendous potential at the efficiency of AA + MA production, and over an optimized catalyst of NSC-Ti/P-0.53, the AA + MA selectivity being 71% (HAc input-based) was achieved at 360 ℃ when the reactant with FA/HAc molar ratio of 5:1 was fed; whereas, a highest space–time-yield (STY) of target products (∼37.2 μmol·g−1·min−1) was obtained with the FA/HAc molar ratio of 1:2.5, which is comparable to the best result reported previously. The detailed analysis of characterizations demonstrated that the change in the Ti/P ratio in the series NASICON catalysts led to the variation in the phase composition, the textural properties, surface titanium oxidation state, etc. thereby tuning the surface acid-base property, which is quite important for the present condensation reaction. More amounts of acidic sites and basic sites as well as their moderate distribution were proved to exert the promotional effects on the formation of AA and MA.

Construction of Complex Macromulticyclic Peptides via Stitching with Formaldehyde and Guanidine.

There is a growing interest in constructing multicyclic peptide structures to expand the chemical space of peptides. Conventional strategies for constructing large peptide structures are limited by the typical reliance on the inflexible coupling between premade templates equipped with fixed reactive handles and peptide substrates via cysteine anchors. Herein, we report the development of a facile three-component condensation reaction of primary alkyl amine, formaldehyde, and guanidine for construction of complex macromulticyclic peptides with novel topologies via lysine anchors. Moreover, the reaction sequences can be orchestrated in different anchor combinations and spatial arrangements to generate various macrocyclic structures crosslinked by distinct fused tetrahydrotriazine linkages. The macrocyclization reactions are selective, efficient, versatile, and workable in both organic and aqueous media. Thus, the condensation reaction provides a smart tool for stitching native peptides in situ using simple methylene threads and guanidine joints in a flexible and programmable manner.

Cesium Loaded on an Al-Modified Silica Support Catalyst for Methyl Acrylate Synthesis by Aldol Condensation of Methyl Acetate and Formaldehyde

An Al-modified silica-supported cesium catalyst was prepared by an incipient wetness impregnation method for the gas-phase aldol condensation reaction of methyl acetate and formaldehyde. The effect of the Al-modified silica support on the structure, specific surface area, and the acid property was studied using X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption–desorption, NH3-temperature programmed desorption, X-ray photoelectron spectroscopy, and Py-IR. Adding the cesium species, the Cs–Al/SiO2 catalyst performed well based on the evaluation results in a fixed-bed reactor. A combination of these characterization and testing results manifests the influence of acid–base properties on the catalytic activity. It was found that the selectivity was related to the amount of weak acid sites and medium-strong base sites. The highest selectivity of methyl acrylate (MA) was obtained at T = 355 °C, LHSV = 0.6 h–1, and Ma/FA/MeOH molar ratio = 1:1:2 over the 10% Cs–3% Al/SiO2 catalyst. Finally, the performance of the optimized catalyst did not exhibit an obvious decrease via three times in situ regeneration.

Nano-sized H-ZSM-5 zeolite catalyzes aldol condensation reaction to prepare methyl acrylate and acrylic acid

An efficient and long-term stable nano-sized N-H-ZSM-5 zeolite catalyst for the one-step aldol condensation reaction of formaldehyde and MAc to produce MA and AA is reported. Its total lifetime reaches up to 226 h by three regeneration runs.

Catalytic Synthesis of Methacrolein via the Condensation of Formaldehyde and Propionaldehyde with L-Proline Intercalated Layered Double Hydroxides

Aldol condensation reactions are very important C–C coupling reactions in organic chemistry. In this study, the catalytic performance of layered double hydroxides (LDHs) in the aldol condensation reaction of formaldehyde (FA) and propionaldehyde (PA) was investigated. The MxAl-LDHs (denoted as re-MxAl–LDHs; M = Ca and Mg; X = 2–4), as heterogeneous basic catalysts toward the aldol condensation reaction, were prepared via a two-step procedure. The catalyst exhibited a high PA conversion (82.59%), but the methacrolein (MAL) selectivity was only 36.01% due to the limitation of the alkali-catalyzed mechanism. On this basis, the direct intercalation of L-proline into LDHs also has been investigated. The influences of several operating conditions, including the temperature, reaction time, and substrate content, on the reaction results were systematically studied, and the optimized reaction conditions were obtained. The optimized Mg3Al–Pro-LDHs catalyst exhibited a much higher MAL selectivity than those of re-MgxAl–LDHs.

Study on the synthesis of 1,3,5-triazinane derivatives on copper-ferrite nanoparticles catalyst

A high efficient method for the synthesis of 1,3,5-triaryltriazinane derivatives is developed by the condensation reaction of amines and formaldehyde followed by spontaneous cyclotrimerization using CuFe2O4 NPs as an environmentally benign catalyst at room temperature. The copper ferrite was easily separated, reused in good repetitive catalytic performance by simple filtration or external magnet. This process was efficient and compatible with wide range of amines to afford a direct access to nitrogen containing compounds in excellent yields up to 99% and high selectivity.

Study on the application of sulfonation catalysis in a new formaldehyde recovery process

This study proposed a new catalytic conversion process using a sulfonated catalyst to promote the condensation reaction of methanol and formaldehyde (FA) to form methylal (DMM). This method can remove FA while generating the valuable chemical product DMM. A series of SiO 2 -xSO 3 H catalysts were developed, and the synergistic effect of the sulfonic acid group vacancy and hydroxyl vacancy contents was evaluated by adjusting the activation temperature and sulfonation ratio. When the activation temperature was 60 °C, the FA yield reached 82.3%, and DMM selectivity was 80.4%. The FA recovery rate was much higher than in other studies. A series of characterization studies revealed that when there were few -SO 3 H groups, the hydroxyl content increased, providing more activation centers for forming the formic acid by-product from FA. The dehydration and condensation of formic acid and methanol formed methyl formate (MF). However, when there were too many -SO 3 H groups, side reactions of methanol and FA occurred preferentially. Therefore, the synergistic effect of the -SO 3 H group and hydroxyl group content was the fundamental reason for the exceptional catalytic performance. Furthermore, in-situ infrared spectroscopy revealed the possible reaction mechanism of methanol and FA on sulfonated silica gel and verified the conclusion drawn from the catalyst characterization. This approach overcomes the disadvantages of the high cost of FA absorption and difficulty of industrialization due to the high reaction temperature and provides the potential to “turn waste into treasure” during FA recovery while providing new avenues to solving the problem of FA pollution.

Model studies on the formation of 2-vinylpyrazine and 2-vinyl-6-methylpyrazine in Maillard-type reactions

Vinylpyrazine compounds are widely present in foods, especially in hot-processed foods, as a class of flavor compounds; however, their formation mechanism in food systems is still unclear. Therefore, in this study, 2-vinylpyrazine and 2-vinyl-6-methylpyrazine were identified in the Maillard model reaction of d-glucose and glycine. The Maillard model reaction of glucose–glycine was constructed to explore the effects of reaction parameters on vinylpyrazines and the related products. The Maillard reaction of [U-13C6] glucose and glycine was established, and alkylpyrazines and formaldehyde were determined via isotope tracing technique as the precursors of vinylpyrazines. The formation of vinylpyrazines was verified by building a model reaction between alkylpyrazines and formaldehyde. The H/D exchange experiment confirmed that the active site of alkylpyrazines was on the methyl group, which was the reaction site for the condensation reaction of alkylpyrazines with formaldehyde. Results suggest that vinylpyrazines are formed by the condensation reaction of alkylpyrazines and formaldehyde.

Bis-Mannich bases as effective corrosion inhibitors for N80 steel in 15% HCl medium

Three novel bis-Mannich bases (named as M-n-M) have been synthesized by condensation reaction of acetophenone and formaldehyde with different aliphatic diamines (n represents the number of carbon atoms in the diamines). Their corrosion inhibition behaviors for N80 steel in 15% HCl solution were evaluated through weight loss measurements, electrochemical tests, scanning electron microscope (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and contact angle measurements. The results showed that the inhibition efficiency was increased with concentration as well as the alkyl chain length of the inhibitor, with the best inhibitor efficiency obtained as 98.20% for 0.3 % M-8-M in 15% HCl at 90 °C. The electrochemical tests revealed these inhibitors are mixed control type. SEM, AFM, XPS and contact angle measurement results revealed that the inhibitors form a compact adsorption layer on N80 steel surface. Adsorption mechanism of the inhibitors obeys the Langmuir isotherm, and physical adsorption and chemical adsorption exist simultaneously. M-8-M was compared with two commercial inhibitors at elevated temperature and gave a satisfactory corrosion rate of 15.13 mm·y−1 on N80 steel in 15% HCl at 120 °C.

Study on the optimized Al2O3–SO3H catalysis for a new formaldehyde recovery process

Formaldehyde is a dangerous chemical present in many industrial waste gases. It can be recovered via catalytic processes; however, many of these require costly precious metals operating under limited reaction temperatures, making their industrialization difficult. This paper proposes a novel method of formaldehyde recovery. A sulfonation catalyst is used to promote a condensation reaction of methanol and formaldehyde to form methylal. Hence, a valuable chemical product is obtained while removing formaldehyde. A series of Al2O3-xSO3H catalysts were designed and the effects of surface acidity and hydroxyl groups on catalytic activity were explored by varying the activation temperature and sulfonation ratio. At an activation temperature of 60 °C, the yield of formaldehyde reaches 78.62% and the selectivity to methylal reaches 80.11%. This recovery rate is much higher than those reported in other studies. Through a series of characterizations, it was found that when the content of –SO3H groups is low, the hydroxyl content increases, which provides more activation centers for the formation of by-product formic acid from formaldehyde, and for the dehydration and condensation of formic acid and methanol to form methyl formate. At the same time, when the content of –SO3H groups is too high, side reactions of methanol and formaldehyde occur preferentially. Therefore, the synergistic effect of the contents of –SO3H and hydroxyl groups is the fundamental cause of the excellent catalytic performance. Based on in-situ infrared research, a possible mechanism of the reaction between methanol and formaldehyde on sulfonated silica gel is proposed, which also verifies the characterization of the catalyst. This research presents new possibilities for solving the problem of formaldehyde pollution.

Study of the toxicological characteristics of water-soluble surface-active substances obtained based on phenol, formaldehyde and sodium sulphite

The object of research is the products of the condensation reaction of phenol, formaldehyde and sodium sulfite in an aqueous medium, in order to obtain water-soluble non-toxic products based on it, which can be proposed for use as surfactants. In the course of the study, the effect of the reaction conditions (ratio of components, temperature and process time) on the quality of the products obtained and their toxicological characteristics are studied. The optimal ratio of the starting reagents phenol: formaldehyde: sodium sulfite: water is selected, which allows to obtain a product with surface-active properties and which contains substances that can be harmful to health. It is recommended that the condensation process be carried out within 1 hour, the optimum reaction temperature is selected at 130 °C. The qualitative characteristics of the obtained product allow to recommend its use as an anionic surfactant. For this, the symptomatic and toxicological properties of the newly developed surfactant, the product of the condensation of phenol, formaldehyde and sodium sulfite in an aqueous medium, are studied. Based on the studies, it is found that with the introduction of such surfactants into the stomach of experimental white rats-females, their slightly irritating effect on the mucous membranes and skin is observed. According to the mortality criterion, with a single oral administration (LD50), the harmful effects of the substance on rats are not noted. According to the research results, the product can be attributed to class IV hazard (low hazard substances) according to GOST 12.1.007.According to toxicological findings, the resulting product can be recommended for use as a textile auxiliary substance, in the technological operations of bleaching, dyeing and printing of fabrics in contact with human skin, as well as additives to concrete mixtures used in the construction industry and other industries

Degradable dual superlyophobic lignocellulosic fibers for high-efficiency oil/water separation

A degradable dual lignocellulosic fiber with superwetting characteristics was successfully fabricated by a strategically adjusted condensation reaction of melamine and formaldehyde, maintaining high efficiency for oil/water mixture separation.

Gaseous catalytic condensation reaction of methyl propionate and formaldehyde in a fluidized bed reactor

ABSTRACTA one‐step aldol condensation reaction of methyl propionate and formaldehyde to produce methyl methacrylate is a promising environmentally sustainable strategy. In this work, the aldol condensation reaction was firstly conducted in a fluidized bed reactor using different types of catalysts. Zirconium and cesium‐loaded SiO2 and Al2O3 acid‐base bifunctional catalysts were prepared by wetness impregnation. Experimental results demonstrated the 15 % Cs‐0.05 %Zr/SiO2 (100–200 mesh) catalyst exhibited excellent catalytic performance. The effects of the supports, reaction temperature, carrier gas flow rate, and feed rate were investigated and optimized. When the flow rate of carrier gas (N2) was 280 cm3/min and the feed rate was 0.6 cm3/min, the methyl propionate conversion was 25.2 % and the methyl methacrylate selectivity could reach 86.1 %. Although the catalytic activity of the 15 %Cs‐0.05 %Zr/SiO2 catalyst dropped with reaction time on stream due to carbon deposition on the surface of catalyst, its activity was restored by a simple regeneration method.

Guerbet reaction of methanol and ethanol catalyzed by CuMgAlOx mixed oxides: Effect of M2+/Al3+ ratio

A series of hydrotalcite-like derived MgAlOx (MA) and CuMgAlOx (CMA) catalysts with various M2+/Al3+ molar ratios were prepared and evaluated by the aldol condensation reaction of formaldehyde and acetaldehyde and Guerbet reaction of methanol and ethanol, respectively. The acidity and the alkalinity as well as the surface copper species of catalysts were characterized by NH3/CO2-TPD, XPS, H2-TPR and H2-TPD techniques. The results show that the catalytic performance of Guerbet reaction of methanol and ethanol is related to the surface Cu0 species and the number of moderate basic sites. Increasing the specific surface area of Cu0 is beneficial to the dehydrogenation of methanol and ethanol to formaldehyde and acetaldehyde. The increase of the amount of moderate basic sites can promote the condensation reaction of formaldehyde and acetaldehyde.